Burt Munro was born in New Zealand in 1899. He bought his first motorcycle, a 600cc Indian Scout, when he was 20 years old and immediately began workiing to improve its top speed of around 60 mph, taking it up to 90 mph.
The original engine was a side valve design so Burt modified it in the mid 30’s based on his own design pattern. Initially disappointed with the lack of extra performance, he kept tuning and by 1940 he’d wrung 120.8 mph out of it to take the New Zealand speed record.
At this stage the con rods were reaching their strain limit so Burt started manufacturing his own out of old Ford truck axles.
The next challenge was overcoming big-end failure. The original lubrication was achieved by a total loss system, which had no direct feed to the big-ends and crank pin. The result was that the rollers often came out blued and fused to the big-end cage.
Eventually Burt made new fly wheels and increased the diameter of the crank pin, which was bored to feed oil direct to the big-ends. He also fitted an Indian Chief oil pump, changing the engine to a dry sump lubrication system.
Over the years, Burt gradually increased the bore and stroke of the scout, increasing the engine to 953cc, casting his own pistons using a large kerosene blow lamp and casting dies he made himself.
Another of his modifications was to the primary transmission. He made sprockets for this and fitted a triplex chain on the primary drive in place of helical gears as this was more efficient.
The clutch remained basically standard with extra springs fitted to cope with the additional power the engine was developing.
On his first trip to Bonneville with the Indian in 1962, Burt achieved a speed of 179 mph, which the people attending ‘Speed Week’ found unbelievable considering the age of both the bike and the rider.
On this day in 1967, Burt claimed the World Record Class S-A 1000cc with an average speed of 183.586mph (one way 190.07mph).
That record was amended to 184.087 mph (296.2593 km/h) in 2014 when Burt’s son noticed the AMA had made a calculation error. This record still stands to this day.
Burt Munro died in 1978 but his story is immortalised in the 2005 film, The World’s Fastest Indian, starring Anthony Hopkins.
